JP7072716B2 - Wireless communication system, transmission / reception method, program, wireless communication base station device, control circuit and control method - Google Patents

Description

The present invention relates to a wireless communication system in which a base station duplicates a packet and transmits it to a mobile terminal.

The traffic volume of mobile networks is on the rise, and the communication speed is also increasing. When LTE (Long Term Evolution) and LTE-A (Long Term Evolution Advanced) are put into full-scale operation, it is expected that the communication speed of mobile networks will be further increased. Furthermore, a fifth-generation wireless access system with the goal of starting services after 2020 for increasingly sophisticated mobile networks is being studied. The 5th generation wireless access system is also called 5G (5th Generation).

In 5G, the system capacity is 1000 times, the data transmission speed is 100 times, the data processing delay is 1/10, and the number of simultaneous connections of communication terminals is 100 times that of the LTE system, further reducing power consumption. , And the realization of cost reduction of the equipment is mentioned as a requirement.

In order to meet such demands, the 3GPP (3rd Generation Partnership Project) is proceeding with the study of 5G standards as Release 15. The 5G radio section technology is called New Radio Access Technology (NR), and several new technologies are being considered. Non-Patent Document 1 describes a packet replication method using a dual connectivity (DC) method or a multi-connectivity (MC) method in which a UE connects and communicates with two eNBs (eNodeBs). And the NR that separates the gNB (next generation NodeB) into a CU (Central Unit) and a plurality of DUs (Distributed Units) are described. Specifically, the DC method is defined by the NR of 3GPP, and is a function that enables the use of additional resources on the secondary node of New RAN (Radio Access Network). Specifically, the MC method is defined by the NR of 3GPP, and is a radio resource backhaul between E-UTRAN (Evolved Universal Terrestrial Radio Access Network) or NR provided by a plurality of different schedulers. The CU controls a plurality of DUs and controls the transmission / reception data processing of each DU. In other words, the MC system and the DC system include a mobile terminal, a plurality of lower base stations that communicate with the mobile terminal, and a higher base station that controls a plurality of lower base stations, and a plurality of data duplicated by the upper base station. Is transmitted to a plurality of lower base stations, and the plurality of lower base stations each transmit data to a mobile terminal.

3GPP R2-1700672

However, according to the above-mentioned conventional technique, the NR uses a packet duplication method in which the same packet is transmitted and received by each gNB using the DC method or the MC method. Therefore, when the packet replication method is used, there is a problem that the radio resource is consumed by the amount of replication. The wireless resource is a resource used for wireless communication, and specifically indicates a frequency and a communication period used for wireless communication.

The present invention has been made in view of the above, and is a wireless communication system in which a base station duplicates a packet and transmits it to a mobile terminal, and is a wireless communication system capable of improving the utilization efficiency of wireless resources. The purpose is to get.

In order to solve the above-mentioned problems and achieve the purpose, a mobile terminal, a plurality of lower base stations including a first lower base station and a second lower base station by communicating with the mobile terminal, and a plurality of lower base stations. A radio that has a higher-level base station that controls In the communication system, the mobile terminal includes a plurality of link control units that receive the first data for each of the plurality of lower base stations, and the first lower base station is the first among the plurality of link control units. When the information indicating that the first data has been received is received from the link control unit of the above, a notification indicating that the transmission of the first data has been completed is transmitted to the upper base station, and the upper base station is the first lower level. Upon receiving the notification from the base station, the second lower base station is characterized by transmitting a message for discarding the first data .

The wireless communication system in which the base station according to the present invention duplicates a packet and transmits it to a mobile terminal has an effect that the efficiency of using wireless resources can be improved.

A block diagram showing a configuration of a wireless communication system according to the first embodiment. A block diagram showing a configuration of a mobile terminal according to the first embodiment. Block diagram showing the configuration of the base station according to the first embodiment The figure which shows the control circuit which concerns on Embodiment 1. The figure which shows the communication environment which separated the base station which concerns on Embodiment 1 into two units. A sequence diagram showing a data flow of the wireless communication system according to the first embodiment. The figure which shows the wireless communication system which concerns on Embodiment 2. A sequence diagram showing a data flow of the wireless communication system according to the second embodiment.

Hereinafter, the wireless communication system according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a block diagram showing a configuration of a wireless communication system according to the first embodiment. The wireless communication system 1 includes a mobile terminal 101, a base station 102, and control stations 105-1 and 105-2. When the control stations 105-1 and 105-2 are shown without distinction, they are referred to as control stations 105. The mobile terminal 101 has a function as a UE. The mobile terminal 101 and the base station 102 transmit and receive data by the NR communication method. The control station 105 has a function as a mobility management Entity (MME) or an S-GW (Serving Gateway). The MME is a logical node that provides mobility control as defined in LTE-A of 3GPP. The S-GW is a packet gateway that accommodates the 3GPP access system specified in LTE-A of 3GPP.

The mobile terminal 101 and the base station 102 can wirelessly communicate with each other, and transmit and receive signals by wireless communication. The mobile terminal 101 includes not only a mobile mobile phone terminal device but also a sensor device. The control protocol applied to the mobile terminal 101 is, for example, a PDCP (Packet Data Convergence Protocol) layer, an RLC (Radio Link Control) layer, a MAC (Medium Access Control) layer, a PHY layer (physical layer), or the like. Hereinafter, the PDCP layer is abbreviated as PDCP. The RLC layer is abbreviated as RLC. The PHY layer is abbreviated as PHY. The MAC layer is abbreviated as MAC. PDCP and RLC are protocols defined by NR of 3GPP. PDCP performs packet data encryption. RLC performs wireless link control.

The base station 102 includes eNBs 103-1 to 103-3. When each of eNB 103-1 to 103-3 is shown without distinction, it is referred to as eNB 103. The eNB 103 and the control station 105 communicate with each other by the S1 interface defined by LTE of 3GPP, and control information is transmitted and received between the eNB 103 and the control station 105. In FIG. 1, one control station 105 is connected to one eNB 103, but one eNB 103 may be connected to a plurality of control stations 105. Communication is performed between the eNBs 103 using the X2 interface defined by LTE of 3GPP, and control information is also transmitted and received between the eNBs 103. The control station 105 controls the eNB 103 and the mobile terminal 101. The control station 105 constitutes an EPC (Evolved Packet Core) network which is a core network, and the base station 102 constitutes an E-UTRAN. EPC and E-UTRAN may be collectively referred to as a network.

The base station 102 may form one cell or may form a plurality of cells. The cell is the communication range of the base station 102. Each cell constitutes coverage, which is a communicable range with the mobile terminal 101. The base station 102 wirelessly communicates with the mobile terminal 101 within the coverage. When the base station 102 constitutes a plurality of cells, each cell can communicate with the mobile terminal 101.

FIG. 2 is a block diagram showing the configuration of the mobile terminal 101 according to the first embodiment. The mobile terminal 101 includes a first protocol processing unit 201, an application unit 202, a first transmission data buffer unit 203, an encoder unit 204, a modulation unit 205, a frequency conversion unit 206, an antenna 207, and demodulation. A unit 208, a decoder unit 209, and a first control unit 210 are provided.

The process when the mobile terminal 101 transmits a signal to the base station 102 will be described. The first protocol processing unit 201 generates control data and outputs it to the first transmission data buffer unit 203. The control data is data used for controlling communication. Specifically, the control data used in the downlink communication from the base station 102 to the mobile terminal 101 is PDCCH (Physical Downlink Control Channel). The control data used in the upstream communication from the mobile terminal 101 to the base station 102 is PUCCH (Physical Uplink Control Channel). The application unit 202 generates user data and outputs it to the first transmission data buffer unit 203. The user data is the content of the actual communication and is the data required by the user of the mobile terminal 101. Specifically, the user data used in the downlink communication is PDSCH (Physical Downlink Shared Channel), and the user data used in the uplink communication is PUSCH (Physical Uplink Shared Channel). The first transmission data buffer unit 203 stores control data and user data. Further, the first transmission data buffer unit 203 outputs control data and user data to the encoder unit 204. The encoder unit 204 performs encoding processing such as error correction on the control data and the user data. The encoder unit 204 outputs the encoded data to the modulation unit 205. Note that there may be data that is directly output from the first transmission data buffer unit 203 to the modulation unit 205 without being encoded by the encoder unit 204. The modulation unit 205 applies modulation processing to the encoded data. The frequency conversion unit 206 converts the modulated data into a baseband signal. Further, the frequency conversion unit 206 converts the baseband signal into a radio frequency signal and outputs it to the antenna 207. The antenna 207 transmits a radio frequency signal to the base station 102 as a transmission signal.

The process when the mobile terminal 101 receives the signal from the base station 102 will be described. The antenna 207 receives a radio signal from the base station 102. The frequency conversion unit 206 converts the received signal of the radio frequency into a baseband signal and outputs it to the demodulation unit 208. The demodulation unit 208 performs demodulation processing on the baseband signal and outputs it to the decoder unit 209. The decoder unit 209 performs decoding processing such as error correction on the demodulated data. Of the decoded data, the decoder unit 209 outputs the control data to the first protocol processing unit 201 and outputs the user data to the application unit 202. The processing of transmitting and receiving signals of the mobile terminal 101 is controlled by the first control unit 210. Therefore, although omitted in FIG. 2, the first control unit 210 is connected to each functional unit other than the antenna 207.

FIG. 3 is a block diagram showing the configuration of the base station 102 according to the first embodiment. The base station 102 includes a first communication unit 301, a second communication unit 302, a second protocol processing unit 303, a second transmission data buffer unit 304, an encoder unit 204, and a modulation unit 205. It includes a frequency conversion unit 206, an antenna 207, a demodulation unit 208, a decoder unit 209, and a second control unit 311.

The process when the base station 102 transmits a signal to the mobile terminal 101 will be described. The first communication unit 301 transmits / receives data to / from the control station 105. The second communication unit 302 transmits / receives data to / from another base station. The first communication unit 301 and the second communication unit 302 each exchange information with the second protocol processing unit 303. The second transmission data buffer unit 304 stores the control data from the second protocol processing unit 303, and the user data and control data from the first communication unit 301 and the second communication unit 302. Further, the second transmission data buffer unit 304 outputs these data to the encoder unit 204.

The encoder unit 204 performs an encoding process such as error correction on the input data. The encoder unit 204 may have data directly output from the second transmission data buffer unit 304 to the modulation unit 205 without performing the encoding process. The modulation unit 205 performs modulation processing on the encoded data. The frequency conversion unit 206 converts the modulation data into a baseband signal and then converts it into a radio frequency signal. The antenna 207 transmits a radio frequency signal to one or more mobile terminals 101.

The process when the base station 102 receives the signal from the mobile terminal 101 will be described. The antenna 207 receives a radio signal from the mobile terminal 101. The frequency conversion unit 206 converts the received signal, which is a received radio signal, from the radio frequency into a baseband signal and outputs it to the demodulation unit 208. The demodulation unit 208 performs demodulation processing on the baseband signal and outputs it to the decoder unit 209. The decoder unit 209 performs decoding processing such as error correction on the demodulated data. Of the decoded data, the control data is transferred to the second protocol processing unit 303, the first communication unit 301, or the second communication unit 302. Of the decoded data, the user data is transferred to the first communication unit 301 or the second communication unit 302. A series of processes of the base station 102 is controlled by the second control unit 311. Therefore, although the second control unit 311 is omitted in FIG. 3, it is connected to each functional unit other than the antenna 207.

First protocol processing unit 201, application unit 202, first transmission data buffer unit 203, encoder unit 204, modulation unit 205, frequency conversion unit 206, antenna 207, demodulation unit 208, decoder unit 209, first control unit. The 210, the first communication unit 301, the second communication unit 302, the second protocol processing unit 303, the second transmission data buffer unit 304, and the second control unit 311 are electronic circuits that perform each processing. It is realized by the processing circuit.

The processing circuit may be dedicated hardware or a control circuit including a memory and a CPU (Central Processing Unit) that executes a program stored in the memory. Here, the memory corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), or a flash memory, a magnetic disk, an optical disk, or the like. FIG. 4 is a diagram showing a control circuit according to the first embodiment. When the processing circuit is a control circuit including a CPU, the control circuit is, for example, the control circuit 10 having the configuration shown in FIG.

As shown in FIG. 4, the control circuit 10 includes a processor 10a which is a CPU and a memory 10b. When it is realized by the control circuit 10 shown in FIG. 4, it is realized by the processor 10a reading and executing the program corresponding to each process stored in the memory 10b. The memory 10b is also used as a temporary memory in each process performed by the processor 10a.

With the widespread use of smartphones and tablet terminals, traffic from cellular wireless communications is increasing explosively. Therefore, there is concern about a shortage of wireless resources. In order to improve the frequency utilization efficiency in response to the shortage of radio resources, it is being considered to reduce the cells configured by the base station 102 into smaller cells and promote spatial separation.

In the cell configuration of the base station so far, the cell composed of eNB has a relatively wide range of coverage, and when it is composed of a plurality of cells, the cell is configured to cover a specific area. rice field. When miniaturization is introduced, the coverage of cells composed of eNBs is narrower than the coverage of cells not composed of eNBs. Therefore, in order for a cell composed of eNBs to cover a specific area, a large number of small-celled eNBs are required.

In the following description, a cell having a relatively large coverage, such as a cell composed of a conventional eNB, is referred to as a macro cell, and an eNB constituting the macro cell is referred to as a macro eNB. Further, a cell having a relatively small coverage, such as a cell made into a small cell, is called a small cell, and an eNB constituting the small cell is called a small eNB.

NR provides three services. The first service is URLLC (Ultra-Reliability Low Latency Communication), which requires low latency and high reliability. The second service is eMBB (enhanced Mobile Broadband), which demands high-speed, large-capacity communication. The third service is mMTC (massive Machine Type Communication) that enables connection of ultra-large capacity terminals. These three services are supposed to use frequencies of 6 GHz or higher and perform wideband communication. However, the high frequency has a feature that the attenuation factor in the air is high and it is difficult to diffract as compared with the frequency of 6 GHz or less used in LTE. Therefore, in order to secure coverage as in LTE, it is necessary to install many base stations 102 having narrow coverage.

When many base stations 102 with narrow coverage are installed, handover often occurs in the mobile terminal 101. In addition, since it is difficult to diffract at a frequency of 6 GHz or higher, when the mobile terminal 101 enters an environment shielded by buildings and obstacles, communication with the base station 102 is interrupted. When such a communication interruption occurs, the mobile terminal 101 during communication temporarily stops data communication, and there arises a problem that communication cannot be performed between the base station 102 and the mobile terminal 101. The first embodiment discloses a method for solving such a problem.

3GPP proposes to separate the base station into two units. The two units are referred to as CU and DU, respectively. Further, a plurality of DUs may be connected to the CU. Multiple options have been proposed for the division of functions between CU and DU. For example, in option 2, it is proposed that the CU has a PDCP and the DU has an RLC, a MAC, and a PHY. Also, as option 3, it is proposed that the CU has PDCP and H-RLC and the DU has L-RLC, MAC, and PHY. Option 3 includes option 3-1. In option 3-1 the L-RLC has the function of dividing the RLC-PDU (Protocol Data Unit), and the H-RLC of the option 3 has the function of confirming delivery and the RLC. It has been proposed to have other functions.

In NR, it has been proposed to apply DC or MC to communication using multiple DUs. By using a plurality of DUs, it is possible to suppress the occurrence of communication interruption between the mobile terminal 101 and the base station 102 even in an environment shielded by buildings and obstacles. For example, even if the mobile terminal 101 is connected to a plurality of DUs and a communication disconnection occurs with any one DU, the data communication is continued by maintaining the connection with the DU other than the DU in which the communication disconnection occurred. It becomes possible to do. Further, by transmitting the same data in a plurality of DUs, the communication becomes redundant, and even if the connection with any one DU or a plurality of DUs is lost, the data communication can be performed without retransmitting. , It is possible to maintain low latency. However, when the same data is transmitted in a plurality of DUs to provide redundancy in communication, radio resources may be insufficient. Here, in the present embodiment, the shortage of wireless resources is suppressed by introducing a mechanism for reducing the retransmission of redundant data.

FIG. 5 is a diagram showing a communication environment in which the base station according to the first embodiment is separated into two units. For example, it is assumed that the mobile terminal 101 is in the environment as shown in FIG. The mobile terminal 101 is connected to a plurality of eNBs 103 having a function as DUs in the multi-connectivity system, and each of the plurality of DUs is connected to the CU 404. The CU is also called a higher-level base station. The DU is also called a lower base station. Hereinafter, the DU of eNB 103-1 will be referred to as DU 401. The DU of eNB 103-2 is called DU 402. The DU of eNB103-3 is called DU403. The DU 401, DU 402, and DU 403 each communicate with the mobile terminal 101. DU401, DU402, and DU403 connect with CU404. The CU 404 controls the transmission and reception of data of the DU 401, DU 402, and DU 403. Further, the CU 404 duplicates the data to be transmitted to the mobile terminal 101 and transmits the data to the DU 401, DU 402, and DU 403. The DU 401, DU 402, and DU 403 each transmit the data duplicated by the CU 404 to the mobile terminal 101.

The DU 401 has a link control unit 407, an access control unit 410, and a physical control unit 413. The link control unit 407 performs RLC processing. The access control unit 410 processes the MAC. The physical control unit 413 performs PHY processing. Hereinafter, the link control unit 407 is also referred to as an RLC 407. The physical control unit 413 is also referred to as PHY413. The access control unit 410 is also referred to as a MAC 410. The DU 402 has a link control unit 408, an access control unit 411, and a physical control unit 414. The link control unit 408 performs RLC processing. The access control unit 411 processes the MAC. The physical control unit 414 performs PHY processing. Hereinafter, the link control unit 408 is also referred to as an RLC 408. The physical control unit 414 is also referred to as PHY414. The access control unit 411 is also referred to as MAC 411. The DU 403 has a link control unit 409, an access control unit 412, and a physical control unit 415. The link control unit 409 performs RLC processing. The access control unit 412 performs MAC processing. The physical control unit 415 performs PHY processing. Hereinafter, the link control unit 409 is also referred to as an RLC 409. The physical control unit 415 is also referred to as PHY415. The access control unit 412 is also referred to as a MAC 412.

The CU 404 includes a first upper control unit 405 and a second upper control unit 406. The first upper control unit 405 processes the SDAP (Service Data Adaptation Protocol) layer. The SDAP layer is abbreviated as SDAP. The second upper control unit 406 performs PDCP processing. The first higher control unit 405 is also referred to as SDAP405. The second upper control unit 406 is also referred to as PDCP406. The mobile terminal 101 includes an upper control unit 420, a data control unit 419, a plurality of link control units 418, 423, 426, a plurality of access control units 417, 422, 425, and a plurality of physical control units 416, 421. It is equipped with 424. The data control unit 419 processes PDCP. The plurality of link control units 418, 423, 426 perform RLC processing. The plurality of access control units 417, 422, 425 perform MAC processing. The plurality of physical control units 416, 421, 424 perform PHY processing. The upper control unit 420 is also referred to as SDAP 420. The data control unit 419 is also referred to as PDCP419. The plurality of link control units 418, 423, 426 are also referred to as RLC 418, 423, 426. The plurality of access control units 417, 422, 425 are also referred to as MAC 417, 422, 425. The plurality of physical control units 416,421,424 are also referred to as PHY416,421,424. SDAP is a protocol that couples IP (Internet Protocol) packets specified in the NR of 3GPP. The data control unit, the link control unit, the access control unit, and the physical control unit are realized by the processing circuit shown in FIG.

The data for the mobile terminal 101 input to the SDAC 405 is duplicated in a plurality of packets by PDCP406 and transferred from the CU 404 to the DU 401, DU 402, and DU 403, respectively. The DU 401 divides the RLC PDU included in the packet by the RLC 407 into the RLC SDU (Service Data Unit) and transfers it to the MAC 410. MAC410 determines the resources that can be transmitted and performs scheduling. The PHY413 converts the RLC SDU into a radio frequency signal and transmits the data to the mobile terminal 101. The DU 401 performs the same data transmission process on the DU 402 and the DU 403. Further, the DU 402 and the DU 403 also perform the same data transmission processing as the DU 401. RLC SDU is also called the first data. The RLC PDU is also called the second data.

FIG. 6 is a sequence diagram showing a data flow of the wireless communication system 1 according to the first embodiment. The first data a transmitted from the RLC 407 of the eNB 103 is received by the RLC 418 of the mobile terminal 101 (step S1). The base station having the RLC 407 is also referred to as a first base station. RLC 407 uses RLC SDU to generate RLC PDUs. The data a is RLC SDU. The data including the header information in one or more RLC SDUs is an RLC PDU. When the RLC PDU is successfully generated and the CRC is OK, an ACK is transmitted from the RLC 418 of the mobile terminal 101 to the RLC 407 of the eNB 103 to inform that the reception was successful (step S2). Further, the RLC 418 transfers the data a to the PDCP 419 in the upper layer (step S3). After confirming that the data a has arrived from the RLC 418 first, the PDCP 419 sends a message to stop the retransmission request to the RLC 423 that has not yet transferred the data a (step S4). In other words, when the PDCP419 receives the data a from any one of the plurality of DUs, the PDCP419 transmits a retransmission request stop message for stopping the request for retransmission of the data a to the RLC423 that has not received the data a. The RLC423 is also referred to as a first link control unit.

Further, the RLC 407 of the eNB 103 transmits a delivery completion notification message to the PDCP 406 (step S5). The delivery completion notification message is a message informing that the RLC 407 has completed transmission of the RLC PDU to the RLC 418. Upon receiving the delivery completion notification, the PDCP406 transmits a retransmission stop message to the RLC 408 of the DU 402 that has not received the data a, that is, has not transmitted the delivery completion notification message (step S6). The base station having the RLC 408 is also referred to as a second base station. Further, the PDCP406 of the CU 404 uses a control message to transmit the discard information indicating that the data a has been discarded to the RLC 423 (step S7). The discard information includes the sequence number of the RLC SDU or RLC PDU that has been stopped resending, and the RLC 423 can stop the retransmission request based on the discard information. Further, the retransmission stop message includes a message for stopping the transmission of the RLC PDU including the transfer to the MAC. Alternatively, the retransmission stop message includes a message for stopping the transmission of the RLC SDU divided in the RLC 408 to the mobile terminal 101 or the transfer to the MAC 411.

If the retransmission request stop message is transmitted to the RLC 423, but the notification of the discard information which is the control message is not received by the RLC 423, the RLC 423 stops the retransmission request of the corresponding RLC SDU or RLC PDU according to the retransmission request stop message. When the notification of the discard information, which is a control message, is transmitted from the PDCP406 and received by the RLC423 of the mobile terminal 101, but the retransmission request stop message is not received from the PDCP419 to the RLC423, the RLC423 does not follow the notification of the discard information. , Requests RLC408 to resend data. When the RLC 423 receives the retransmission request stop message, but the data a is transmitted from the RLC 408, the RLC 423 receives the data a, generates an RLC PDU using the RLC SDU, and transfers the data a to the PDCP 419. do.

If a retransmission stop message is transmitted from PDCP406 to RLC408 and RLC408 receives a retransmission request from RLC423 while the RLC 408 is discarding the RLC PDU or RLC SDU that is the target of the retransmission stop, the RLC 408 is the RLC SDU that is the target of the retransmission stop. Or do not resend the RLC PDU.

As described above, in the present embodiment, the eNB 103 is prevented from retransmitting the data of the packet duplicated by the PDCP 406, which is the late arrival data for the mobile terminal 101. It is possible to suppress the consumption of wireless resources with the mobile terminal 101 and provide a communication system having high speed, high reliability and low delay.

Embodiment 2.
FIG. 7 is a diagram showing a wireless communication system according to the second embodiment. In FIG. 7, RLC is divided into H-RLC and L-RLC. The mobile terminal 101a includes an upper link control unit 702 and a lower link control unit 701, 703, 704. The upper link control unit 702 processes the H-RLC. The lower link control unit 701, 703, 704 processes L-RLC. The upper link control unit 702 is also referred to as an H-RLC702. The lower link control units 701,703,704 are also referred to as L-RLC701,703,704, respectively.

FIG. 8 is a sequence diagram showing a data flow of the wireless communication system 1a according to the second embodiment. The data a transmitted from the RLC 407 is divided into one or a plurality of RLC SDUs and transmitted (step S11). Data b that is missing or damaged while one or more RLC SDUs are transmitting from the eNB 103 to the mobile terminal 101.

The L-RLC701 transmits the data b from the RLC SDU to the H-RLC702 without binding to the RLC PDU (step S12). Similarly, the data a transmitted from the RLC 408 is divided into one or a plurality of RLC SDUs and transmitted to the L-RLC703 (step S13). Data c that is missing or damaged while one or more RLC SDUs are transmitting from the eNB 103 to the mobile terminal 101. In L-RLC703, this data c is transferred from RLC SDU to H-RLC702 without being bound to RLC PDU (step S14).

L-RLC701 and L-RLC703 transmit an ACK to RLC407 and RLC408, respectively, and RLC407 and RLC408 send a delivery completion notification to PCDP406. H-RLC702, which has received data from L-RLC701 and L-RLC703, combines data b and data c. That is, RLC PDU is generated from RLC SDU transmitted by a plurality of L-RLCs. Further, H-RLC702 synthesizes RLC SDUs having the same sequence number to each other to generate RLC SDUs lacking each other. PDCP406 has the feature of designating RLC 407 and RLC 408 the size of dividing the RLC PDU into RLC SDUs, making the RLC SDUs produced by two or more RLCs equivalent or the same.

As described above, in the present embodiment, even when the RLC is divided into the H-RLC and the L-RLC, the data of the packet duplicated by the PDCP406 that is the posterior to the mobile terminal 101a is displayed. By preventing the eNB 103 from retransmitting, the radio resource between one or more eNB 103 and the mobile terminal 101a can be released, and a communication system having high speed, high reliability, and low delay can be provided.

The configuration shown in the above embodiments shows an example of the contents of the present invention, can be combined with another known technique, and is one of the configurations as long as it does not deviate from the gist of the present invention. It is also possible to omit or change the part.

1,1a wireless communication system, 10 control circuit, 10a processor, 10b memory, 101, 101a mobile terminal, 102 base station, 103, 103-1 to 103-3 eNB, 105, 105-1, 105-2 control station, 201 1st protocol processing unit, 202 application unit, 203 1st transmission data buffer unit, 204 encoder unit, 205 modulation unit, 206 frequency conversion unit, 207 antenna, 208 demodulation unit, 209 decoder unit, 210 1st control Unit, 301 1st communication unit, 302 2nd communication unit, 303 2nd protocol processing unit, 304 2nd transmission data buffer unit, 311 2nd control unit, 401, 402, 403 DU (lower base station) ), 404 CU (upper base station), 405,420 SDAP, 406,419 PDCP, 407,408,409,418,423,426 RLC, 410,411,421,417,422,425 MAC, 413,414 415,416,421,424 PHY, 701,703,704 L-RLC, 702 H-RLC.

Claims (9)

The mobile terminal includes a plurality of lower base stations including a first lower base station and a second lower base station that communicate with the mobile terminal, and a higher base station that controls the plurality of lower base stations. A wireless communication system in which a plurality of first data duplicated by a base station is transmitted to the plurality of lower base stations, and the plurality of lower base stations transmit the first data to the mobile terminal, respectively.
The mobile terminal is
Each of the plurality of lower base stations is provided with a plurality of link control units for receiving the first data.
The first lower base station is
When the information indicating that the first data has been received is received from the first link control unit among the plurality of link control units, it indicates that the transmission of the first data has been completed to the upper base station. Send a notification,
The upper base station is
Upon receiving the notification from the first lower base station, the second lower base station is transmitted a message for discarding the first data.
A wireless communication system characterized by that. The mobile terminal includes a plurality of lower base stations including a first lower base station and a second lower base station that communicate with the mobile terminal, and a higher base station that controls the plurality of lower base stations. The plurality of first data duplicated by the base station is transmitted to the plurality of lower base stations, the plurality of lower base stations transmit the first data to the mobile terminal, and the mobile terminal is the plurality of. A transmission / reception method in a wireless communication system including a plurality of link control units for receiving the first data for each lower base station.
When the first lower base station receives information indicating that the first data has been received from the first link control unit among the plurality of link control units, the first lower base station receives the information indicating that the first data has been received. Steps to send a notification that the data has been sent, and
When the upper base station receives the notification from the first lower base station, the upper base station transmits a message for causing the second lower base station to discard the first data.
A transmission / reception method characterized by including. The mobile terminal includes a plurality of lower base stations including a first lower base station and a second lower base station that communicate with the mobile terminal, and a higher base station that controls the plurality of lower base stations. The plurality of first data duplicated by the base station is transmitted to the plurality of lower base stations, the plurality of lower base stations transmit the first data to the mobile terminal, and the mobile terminal is the plurality of. For a wireless communication system including a plurality of link control units for receiving the first data for each lower base station,
When the first lower base station receives information indicating that the first data has been received from the first link control unit among the plurality of link control units, the first lower base station receives the information indicating that the first data has been received. Steps to send a notification that the data has been sent, and
When the upper base station receives the notification from the first lower base station, the upper base station transmits a message for causing the second lower base station to discard the first data.
A program characterized by executing. A plurality of first data duplicated by the mobile terminal, including a mobile terminal, a plurality of wireless communication base station devices that communicate with the mobile terminal, and a higher-level base station that controls the plurality of wireless communication base station devices. Is transmitted to the plurality of wireless communication base station devices, the plurality of wireless communication base station devices transmit the first data to the mobile terminal, and the mobile terminal transmits the first data to the mobile terminal for each of the plurality of wireless communication base station devices. The wireless communication base station apparatus in a wireless communication system including a plurality of link control units for receiving the first data.
When the information indicating that the first data has been received is received from the first link control unit among the plurality of link control units, it indicates that the transmission of the first data has been completed to the higher-level base station. A wireless communication base station device characterized by transmitting notifications. The mobile terminal is provided with a plurality of lower base stations including a first lower base station and a second lower base station that communicate with the mobile terminal, and a wireless communication base station apparatus that controls the plurality of lower base stations. In a wireless communication system in which a plurality of first data duplicated by the wireless communication base station apparatus is transmitted to the plurality of lower base stations, and the plurality of lower base stations transmit the first data to the mobile terminal, respectively. The wireless communication base station device,
Upon receiving a notification from the first lower base station indicating that the transmission of the first data has been completed, a message for causing the second lower base station to discard the first data is transmitted.
A wireless communication base station device characterized by that. A plurality of first data duplicated by the mobile terminal, including a mobile terminal, a plurality of wireless communication base station devices that communicate with the mobile terminal, and a higher-level base station that controls the plurality of wireless communication base station devices. Is transmitted to the plurality of wireless communication base station devices, the plurality of wireless communication base station devices transmit the first data to the mobile terminal, and the mobile terminal transmits the first data to the mobile terminal for each of the plurality of wireless communication base station devices. A control circuit for the wireless communication base station apparatus in a wireless communication system including a plurality of link control units for receiving the first data.
When the information indicating that the first data has been received is received from the first link control unit among the plurality of link control units, it indicates that the transmission of the first data has been completed to the upper base station. The process of sending a notification
A control circuit, characterized in that the wireless communication base station apparatus is executed. The mobile terminal is provided with a plurality of lower base stations including a first lower base station and a second lower base station that communicate with the mobile terminal, and a wireless communication base station apparatus that controls the plurality of lower base stations. In a wireless communication system in which a plurality of first data duplicated by the wireless communication base station apparatus is transmitted to the plurality of lower base stations, and the plurality of lower base stations transmit the first data to the mobile terminal, respectively. A control circuit for the wireless communication base station device.
When a notification indicating that the first data has been transmitted is received from the first lower base station, a process of transmitting a message to the second lower base station to discard the first data.
A control circuit, characterized in that the wireless communication base station apparatus is executed. A plurality of first data duplicated by the mobile terminal, including a mobile terminal, a plurality of wireless communication base station devices that communicate with the mobile terminal, and a higher-level base station that controls the plurality of wireless communication base station devices. Is transmitted to the plurality of wireless communication base station devices, the plurality of wireless communication base station devices transmit the first data to the mobile terminal, and the mobile terminal transmits the first data to the mobile terminal for each of the plurality of wireless communication base station devices. A control method for the wireless communication base station apparatus in a wireless communication system including a plurality of link control units for receiving the first data.
Information indicating that the first data has been received is received from the first link control unit among the plurality of link control units.
When the information is received, a notification indicating that the first data has been transmitted is transmitted to the higher-level base station.
A control method characterized by that. The mobile terminal is provided with a plurality of lower base stations including a first lower base station and a second lower base station that communicate with the mobile terminal, and a wireless communication base station apparatus that controls the plurality of lower base stations. In a wireless communication system in which a plurality of first data duplicated by the wireless communication base station apparatus is transmitted to the plurality of lower base stations, and the plurality of lower base stations transmit the first data to the mobile terminal, respectively. A control method for the wireless communication base station device.
Upon receiving the notification from the first lower base station indicating that the transmission of the first data has been completed, the notification is received.
Upon receiving the notification, a message is transmitted to the second lower base station to discard the first data.
A control method characterized by that.

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